wp-calypso/packages/components/src/progress-bar/style.scss

.progress-bar {
	width: 100%;
	display: inline-block;
	position: relative;
	height: 9px;
	background-color: var(--color-neutral-10);
	/* stylelint-disable-next-line scales/radii */
	border-radius: 4.5px;

	&.is-compact {
		height: 4px;
	}
}

.progress-bar__progress {
	display: inline-block;
	position: absolute;
	top: 0;
	left: 0;
	height: 100%;
	background-color: var(--studio-blue-50);
	/* stylelint-disable-next-line scales/radii */
	border-radius: 4.5px;
	transition: width 200ms;

	@media (prefers-reduced-motion: reduce) {
		transition: none;
	}
}

/* Percentage bar */
.percentage-bar {
	border-radius: 0;
	height: 8px;
	width: 150px;

	.progress-bar__progress {
		border-radius: 0;
	}
}

.progress-bar.is-pulsing .progress-bar__progress {
	animation: progress-bar-animation 3300ms infinite linear;
	background-size: 50px 100%;
	background-image: linear-gradient(-45deg, var(--studio-blue-50) 28%, var(--studio-blue-30) 28%, var(--studio-blue-30) 72%, var(--studio-blue-50) 72%);

	@media (prefers-reduced-motion: reduce) {
		animation: none;
	}
}

@keyframes progress-bar-animation {
	0% {
		background-position: 100px 0;
	}
}